Jellyfish stings are hazardous for anyone who enters a marine environment anywhere in the world. Jellyfish are most common in the tropics, but are found in waters ranging from tropical to arctic. Stings are more common in the summer months due to the increased recreational exposure to the marine environment as well as the seasonal patterns of jellyfish.
Recent increases in the jellyfish population have made jellyfish stings a more frequent occurrence, and a more common concern for would-be swimmers. Some marine scientists attribute the recent proliferation of jellyfish to mankind's impact on marine life; jellyfish may merely be taking the place of already overfished creatures. Since jellyfish feed on the same kinds of prey as many species of fishes, depletion of fish populations allows jellyfish to move in. Sampling sea life in certain heavily fished regions has shown that jellyfish have actually overtaken fish in terms of the biomass they contribute to these ocean regions. Additionally, increased nutrients in the water, ascribed to agricultural runoff and urban by-products, may also be a factor in the recent proliferation of jellyfish numbers. High levels of nutrients provide nourishment for the small organisms on which jellyfish feed. In waters where there is eutrophication, low oxygen levels often result, favoring jellyfish, which thrive in less oxygen-rich water than fish can tolerate.
Jellyfish, or coelenterates, are marine invertebrates belonging to the Scyphozoan class, and in turn the phylum Cnidaria. They are related to corals, hydra and sea anemones. The body of an adult jellyfish is composed of a bell-shaped, jellylike substance enclosing its internal structure, from which the creature's tentacles suspend. Each tentacle is covered with stinging cells (cnidocytes) that can sting or kill other animals: most jellyfish use them to secure prey or as a defense mechanism. In its adult form, a jellyfish is composed of 94-98% water and can be found in every pelagic area of the world.
Most jellyfish have tentacles or oral arms coated with thousands of the stinging cells called cnidocytes containing a microscopic, toxin-filled harpoon, a nematocysts. Generally, each nematocyst has a “trigger” (cnidocil) paired with a capsule containing a coiled stinging filament, as well as barbs on the exterior. Upon contact, the filament will swiftly unwind, launch into the target, and inject toxins. It can then pull the victim into its mouth, if appropriate. In addition to discharging toxin, the nematocysts activate the surrounding cnidocytes to increase the total volume of venom injected. Importantly, the nematocysts are still able to function when separated from the jellyfish, making deactivation and removal of these stingers a key element of treatment.
There are several types of coelenterate toxins, but all consist of a complex mixture of proteins and enzymes. The most severe envenomations can occasionally induce systemic responses such as nausea, headache, and chills and even more rarely can induce severe systemic reactions such as cardiac arrhythmia, respiratory dysfunction, psychosis, and muscular spasm. Yet the major feature of most stings is the rash and associated pain, which is caused by a combination of several elements of the venom. Most envenomations result in pain that can be severe, but is usually self-limited. The duration of the symptoms of minor stings ranges from a few minutes to several hours, weeks, or longer depending upon the jellyfish species, the extent of the sting, the presenting symptoms, and the physiology of the individual. Most of the effects, both mild and severe, are caused by the actions of the venom, not an allergic reaction. The local reaction to most jellyfish envenomations includes local reactions such as pain, pruritus, paresthesias such as numbness, burning, or throbbing, inflammatory rash, blistering, and swelling.
Common anecdotal treatment of an envenomation is the liberal application of 5 percent acetic acid (household vinegar) to the affected areas. The acetic acid is supposed to deactivate any non-discharged nematocysts, however the results below indicate that application of vinegar may actually trigger firing of additional nematocysts. Additionally, the nematocysts of certain species of jellyfish may not be effectively deactivated by vinegar. Other topical decontaminants such as baking soda, isopropyl alcohol, a paste of meat tenderizer or papaya, concentrated citrus juice, olive oil and quarter strength household ammonia are often recommended, but have varying or little effectiveness. Fresh water or an organic solvent such as gasoline or turpentine must not be applied. Such agents may cause the firing of more nematocysts and worsen the sting or damage the skin directly.
After deactivation, general treatment protocols recommend that the sting area should be exposed and any remaining tentacles or nematocysts removed. Various techniques for removal are recommended, from rubbing with sand or a paste of mud or sand (which has been shown to induce additional nematocyst firing and increase pain), to shaving the affected area with shaving cream and a razor or other available object such as a credit card or seashell. However, most of these traditional or “home” remedies prove slow-acting and/or ineffective at best, and at worst, some of the above remedies can result in the release of more toxin and an increase in pain. Meanwhile, the patient continues to experience pain and other symptoms of the sting for several hours or days.
No commercial preparations for the treatment of jellyfish stings appear to exist, and topical preparations for other skin conditions such as sunburn prove ineffective. While the above-described traditional remedies, such as vinegar, may have limited deactivating properties, such formulations still lack an effective pain relief, particularly in the short term. Thus, presently a formulation that adequately and quickly treats the pain and swelling associated with jellyfish stings, and other animal stings and skin irritations is not available and would be desirable for at least the above reasons.